// This header contains common, non-processor-specific data structures and
// constants for the ELF file format.
//
-// The details of the ELF32 bits in this file are largely based on
-// the Tool Interface Standard (TIS) Executable and Linking Format
-// (ELF) Specification Version 1.2, May 1995. The ELF64 stuff is not
-// standardized, as far as I can tell. It was largely based on information
-// I found in OpenBSD header files.
+// The details of the ELF32 bits in this file are largely based on the Tool
+// Interface Standard (TIS) Executable and Linking Format (ELF) Specification
+// Version 1.2, May 1995. The ELF64 is based on HP/Intel definition of the
+// ELF-64 object file format document, Version 1.5 Draft 2 May 27, 1998
//
//===----------------------------------------------------------------------===//
#ifndef CODEGEN_ELF_H
#define CODEGEN_ELF_H
+#include "llvm/CodeGen/BinaryObject.h"
#include "llvm/CodeGen/MachineRelocation.h"
-#include "llvm/Support/DataTypes.h"
-#include <cstring>
+#include "llvm/System/DataTypes.h"
namespace llvm {
- class GlobalVariable;
+ class GlobalValue;
// Identification Indexes
enum {
ET_HIPROC = 0xffff // Processor-specific
};
- // Object file classes.
- enum {
- ELFCLASS32 = 1, // 32-bit object file
- ELFCLASS64 = 2 // 64-bit object file
- };
-
- // Object file byte orderings.
- enum {
- ELFDATA2LSB = 1, // Little-endian object file
- ELFDATA2MSB = 2 // Big-endian object file
- };
-
// Versioning
enum {
EV_NONE = 0,
EV_CURRENT = 1
};
- struct ELFHeader {
- // e_machine - This field is the target specific value to emit as the
- // e_machine member of the ELF header.
- unsigned short e_machine;
-
- // e_flags - The machine flags for the target. This defaults to zero.
- unsigned e_flags;
-
- // e_size - Holds the ELF header's size in bytes
- unsigned e_ehsize;
-
- // Endianess and ELF Class (64 or 32 bits)
- unsigned ByteOrder;
- unsigned ElfClass;
-
- unsigned getByteOrder() const { return ByteOrder; }
- unsigned getElfClass() const { return ElfClass; }
- unsigned getSize() const { return e_ehsize; }
- unsigned getMachine() const { return e_machine; }
- unsigned getFlags() const { return e_flags; }
-
- ELFHeader(unsigned short machine, unsigned flags,
- bool is64Bit, bool isLittleEndian)
- : e_machine(machine), e_flags(flags) {
- ByteOrder = is64Bit ? ELFCLASS64 : ELFCLASS32;
- ElfClass = isLittleEndian ? ELFDATA2LSB : ELFDATA2MSB;
- e_ehsize = is64Bit ? 64 : 52;
- }
+ /// ELFSym - This struct contains information about each symbol that is
+ /// added to logical symbol table for the module. This is eventually
+ /// turned into a real symbol table in the file.
+ struct ELFSym {
+
+ // ELF symbols are related to llvm ones by being one of the two llvm
+ // types, for the other ones (section, file, func) a null pointer is
+ // assumed by default.
+ union {
+ const GlobalValue *GV; // If this is a pointer to a GV
+ const char *Ext; // If this is a pointer to a named symbol
+ } Source;
+
+ // Describes from which source type this ELF symbol comes from,
+ // they can be GlobalValue, ExternalSymbol or neither.
+ enum {
+ isGV, // The Source.GV field is valid.
+ isExtSym, // The Source.ExtSym field is valid.
+ isOther // Not a GlobalValue or External Symbol
+ };
+ unsigned SourceType;
+
+ bool isGlobalValue() const { return SourceType == isGV; }
+ bool isExternalSym() const { return SourceType == isExtSym; }
+
+ // getGlobalValue - If this is a global value which originated the
+ // elf symbol, return a reference to it.
+ const GlobalValue *getGlobalValue() const {
+ assert(SourceType == isGV && "This is not a global value");
+ return Source.GV;
+ };
+
+ // getExternalSym - If this is an external symbol which originated the
+ // elf symbol, return a reference to it.
+ const char *getExternalSymbol() const {
+ assert(SourceType == isExtSym && "This is not an external symbol");
+ return Source.Ext;
+ };
+
+ // getGV - From a global value return a elf symbol to represent it
+ static ELFSym *getGV(const GlobalValue *GV, unsigned Bind,
+ unsigned Type, unsigned Visibility) {
+ ELFSym *Sym = new ELFSym();
+ Sym->Source.GV = GV;
+ Sym->setBind(Bind);
+ Sym->setType(Type);
+ Sym->setVisibility(Visibility);
+ Sym->SourceType = isGV;
+ return Sym;
+ }
+
+ // getExtSym - Create and return an elf symbol to represent an
+ // external symbol
+ static ELFSym *getExtSym(const char *Ext) {
+ ELFSym *Sym = new ELFSym();
+ Sym->Source.Ext = Ext;
+ Sym->setBind(STB_GLOBAL);
+ Sym->setType(STT_NOTYPE);
+ Sym->setVisibility(STV_DEFAULT);
+ Sym->SourceType = isExtSym;
+ return Sym;
+ }
+
+ // getSectionSym - Returns a elf symbol to represent an elf section
+ static ELFSym *getSectionSym() {
+ ELFSym *Sym = new ELFSym();
+ Sym->setBind(STB_LOCAL);
+ Sym->setType(STT_SECTION);
+ Sym->setVisibility(STV_DEFAULT);
+ Sym->SourceType = isOther;
+ return Sym;
+ }
+
+ // getFileSym - Returns a elf symbol to represent the module identifier
+ static ELFSym *getFileSym() {
+ ELFSym *Sym = new ELFSym();
+ Sym->setBind(STB_LOCAL);
+ Sym->setType(STT_FILE);
+ Sym->setVisibility(STV_DEFAULT);
+ Sym->SectionIdx = 0xfff1; // ELFSection::SHN_ABS;
+ Sym->SourceType = isOther;
+ return Sym;
+ }
+
+ // getUndefGV - Returns a STT_NOTYPE symbol
+ static ELFSym *getUndefGV(const GlobalValue *GV, unsigned Bind) {
+ ELFSym *Sym = new ELFSym();
+ Sym->Source.GV = GV;
+ Sym->setBind(Bind);
+ Sym->setType(STT_NOTYPE);
+ Sym->setVisibility(STV_DEFAULT);
+ Sym->SectionIdx = 0; //ELFSection::SHN_UNDEF;
+ Sym->SourceType = isGV;
+ return Sym;
+ }
+
+ // ELF specific fields
+ unsigned NameIdx; // Index in .strtab of name, once emitted.
+ uint64_t Value;
+ unsigned Size;
+ uint8_t Info;
+ uint8_t Other;
+ unsigned short SectionIdx;
+
+ // Symbol index into the Symbol table
+ unsigned SymTabIdx;
+
+ enum {
+ STB_LOCAL = 0, // Local sym, not visible outside obj file containing def
+ STB_GLOBAL = 1, // Global sym, visible to all object files being combined
+ STB_WEAK = 2 // Weak symbol, like global but lower-precedence
+ };
+
+ enum {
+ STT_NOTYPE = 0, // Symbol's type is not specified
+ STT_OBJECT = 1, // Symbol is a data object (variable, array, etc.)
+ STT_FUNC = 2, // Symbol is executable code (function, etc.)
+ STT_SECTION = 3, // Symbol refers to a section
+ STT_FILE = 4 // Local, absolute symbol that refers to a file
+ };
+
+ enum {
+ STV_DEFAULT = 0, // Visibility is specified by binding type
+ STV_INTERNAL = 1, // Defined by processor supplements
+ STV_HIDDEN = 2, // Not visible to other components
+ STV_PROTECTED = 3 // Visible in other components but not preemptable
+ };
+
+ ELFSym() : SourceType(isOther), NameIdx(0), Value(0),
+ Size(0), Info(0), Other(STV_DEFAULT), SectionIdx(0),
+ SymTabIdx(0) {}
+
+ unsigned getBind() const { return (Info >> 4) & 0xf; }
+ unsigned getType() const { return Info & 0xf; }
+ bool isLocalBind() const { return getBind() == STB_LOCAL; }
+ bool isFileType() const { return getType() == STT_FILE; }
+
+ void setBind(unsigned X) {
+ assert(X == (X & 0xF) && "Bind value out of range!");
+ Info = (Info & 0x0F) | (X << 4);
+ }
+
+ void setType(unsigned X) {
+ assert(X == (X & 0xF) && "Type value out of range!");
+ Info = (Info & 0xF0) | X;
+ }
+
+ void setVisibility(unsigned V) {
+ assert(V == (V & 0x3) && "Visibility value out of range!");
+ Other = V;
+ }
};
/// ELFSection - This struct contains information about each section that is
/// emitted to the file. This is eventually turned into the section header
/// table at the end of the file.
- struct ELFSection {
-
+ class ELFSection : public BinaryObject {
+ public:
// ELF specific fields
- std::string Name; // Name of the section.
- unsigned NameIdx; // Index in .shstrtab of name, once emitted.
- unsigned Type;
- unsigned Flags;
- uint64_t Addr;
- unsigned Offset;
- unsigned Size;
- unsigned Link;
- unsigned Info;
- unsigned Align;
- unsigned EntSize;
+ unsigned NameIdx; // sh_name - .shstrtab idx of name, once emitted.
+ unsigned Type; // sh_type - Section contents & semantics
+ unsigned Flags; // sh_flags - Section flags.
+ uint64_t Addr; // sh_addr - The mem addr this section is in.
+ unsigned Offset; // sh_offset - Offset from the file start
+ unsigned Size; // sh_size - The section size.
+ unsigned Link; // sh_link - Section header table index link.
+ unsigned Info; // sh_info - Auxillary information.
+ unsigned Align; // sh_addralign - Alignment of section.
+ unsigned EntSize; // sh_entsize - Size of entries in the section e
// Section Header Flags
enum {
SHT_REL = 9, // Relocation entries; no explicit addends.
SHT_SHLIB = 10, // Reserved.
SHT_DYNSYM = 11, // Symbol table.
- SHT_LOPROC = 0x70000000, // Lowest processor architecture-specific type.
- SHT_HIPROC = 0x7fffffff, // Highest processor architecture-specific type.
+ SHT_LOPROC = 0x70000000, // Lowest processor arch-specific type.
+ SHT_HIPROC = 0x7fffffff, // Highest processor arch-specific type.
SHT_LOUSER = 0x80000000, // Lowest type reserved for applications.
SHT_HIUSER = 0xffffffff // Highest type reserved for applications.
};
/// SectionIdx - The number of the section in the Section Table.
unsigned short SectionIdx;
- /// SectionData - The actual data for this section which we are building
- /// up for emission to the file.
- std::vector<unsigned char> SectionData;
-
- /// Relocations - The relocations that we have encountered so far in this
- /// section that we will need to convert to MachORelocation entries when
- /// the file is written.
- std::vector<MachineRelocation> Relocations;
+ /// Sym - The symbol to represent this section if it has one.
+ ELFSym *Sym;
- /// Section Header Size
- static unsigned getSectionHdrSize(bool is64Bit)
- { return is64Bit ? 64 : 40; }
+ /// getSymIndex - Returns the symbol table index of the symbol
+ /// representing this section.
+ unsigned getSymbolTableIndex() const {
+ assert(Sym && "section not present in the symbol table");
+ return Sym->SymTabIdx;
+ }
- ELFSection(const std::string &name)
- : Name(name), Type(0), Flags(0), Addr(0), Offset(0), Size(0),
- Link(0), Info(0), Align(0), EntSize(0) {}
+ ELFSection(const std::string &name, bool isLittleEndian, bool is64Bit)
+ : BinaryObject(name, isLittleEndian, is64Bit), Type(0), Flags(0), Addr(0),
+ Offset(0), Size(0), Link(0), Info(0), Align(0), EntSize(0), Sym(0) {}
};
- /// ELFSym - This struct contains information about each symbol that is
- /// added to logical symbol table for the module. This is eventually
- /// turned into a real symbol table in the file.
- struct ELFSym {
- const GlobalValue *GV; // The global value this corresponds to.
-
- // ELF specific fields
- unsigned NameIdx; // Index in .strtab of name, once emitted.
- uint64_t Value;
- unsigned Size;
- uint8_t Info;
- uint8_t Other;
- unsigned short SectionIdx;
-
- enum {
- STB_LOCAL = 0,
- STB_GLOBAL = 1,
- STB_WEAK = 2
- };
-
- enum {
- STT_NOTYPE = 0,
- STT_OBJECT = 1,
- STT_FUNC = 2,
- STT_SECTION = 3,
- STT_FILE = 4
- };
+ /// ELFRelocation - This class contains all the information necessary to
+ /// to generate any 32-bit or 64-bit ELF relocation entry.
+ class ELFRelocation {
+ uint64_t r_offset; // offset in the section of the object this applies to
+ uint32_t r_symidx; // symbol table index of the symbol to use
+ uint32_t r_type; // machine specific relocation type
+ int64_t r_add; // explicit relocation addend
+ bool r_rela; // if true then the addend is part of the entry
+ // otherwise the addend is at the location specified
+ // by r_offset
+ public:
+ uint64_t getInfo(bool is64Bit) const {
+ if (is64Bit)
+ return ((uint64_t)r_symidx << 32) + ((uint64_t)r_type & 0xFFFFFFFFL);
+ else
+ return (r_symidx << 8) + (r_type & 0xFFL);
+ }
- ELFSym(const GlobalValue *gv) : GV(gv), NameIdx(0), Value(0),
- Size(0), Info(0), Other(0),
- SectionIdx(ELFSection::SHN_UNDEF) {}
+ uint64_t getOffset() const { return r_offset; }
+ int64_t getAddend() const { return r_add; }
- void SetBind(unsigned X) {
- assert(X == (X & 0xF) && "Bind value out of range!");
- Info = (Info & 0x0F) | (X << 4);
- }
- void SetType(unsigned X) {
- assert(X == (X & 0xF) && "Type value out of range!");
- Info = (Info & 0xF0) | X;
- }
+ ELFRelocation(uint64_t off, uint32_t sym, uint32_t type,
+ bool rela = true, int64_t addend = 0) :
+ r_offset(off), r_symidx(sym), r_type(type),
+ r_add(addend), r_rela(rela) {}
};
} // end namespace llvm
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